Effects of SiO2 nanoparticles dispersion on concrete fracture toughness

Failure of concrete structures is usually accompanied by expansion of interior cracks due to stress concentration at the cracks tip. This phenomenon shows the importance of examination of the failure behavior of concrete structures. For this purpose, 4 types of concrete samples with different amounts of nano-SiO2 (0%, 0.2%, 0.5%, and 0.8%) were made to prepare some Central Straight-through Crack Brazilian Disk (CSCBD) specimens. The key focus of the investigation conducted was to investigate two assumptions. First, to check the pure mode I (tension) and pure mode II (shear) by compressing the standard discs with central cracks by an angle of 0° and 27° with respect to the loading axis; Second, to investigate the failure behavior of control and binary blended concrete using Acoustic Emission (AE) technique. The results show that the highest fracture toughness in both mode I and II was obtained at 0.5% of nano-SiO2 blended concrete. Also the behavior of micro cracks which transforms from tensile mode to shear mode could be sensible.